Preparation and use of tetrasubstituted fluorenyl catalysts for polymerization of olefins

ABSTRACT

Catalyst compositions and processes for the polymerization of ethylenically unsaturated monomers to produce polymers, including copolymers or homopolymers. Such monomers include ethylene, C 3+  alpha olefins and substituted vinyl compounds, such as styrene and vinyl chloride. The polymerization catalyst characterized by the formula B(FluL)MQ n  in which Flu is a fluorenyl group substituted at at least the 2,7- and 3,6-positions by hydrocarbyl groups, preferably relatively bulky hydrocarbyl groups. L is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group or a heteroorgano group, XR, in which X is a heteroatom from Group 15 or 16 of the Periodic Table of Elements, such as nitrogen, R is an alkyl group, a cycloalkyl group or an aryl group and B is a structural bridge extending between the groups L and Flu, which imparts stereorigidity to the ligand structure, M is a Group 4 or Group 5 transition metal, such as titanium, zirconium or hafnium and Q is selected from the group consisting of chlorine, bromine, iodine, an alkyl group, an amino group, an aromatic group and mixtures thereof, with n being 1 or 2.

FIELD OF THE INVENTION

This invention relates to olefin polymerization catalysts and their use in the polymerization of ethylenically unsaturated monomers.

BACKGROUND OF THE INVENTION

Olefin polymers such as polyethylene, polypropylene, which may be atactic or stereospecific, such as isotactic or syndiotactic, and ethylene-higher alpha olefin copolymers, such as ethylene-propylene copolymers can be produced under various polymerization conditions and employing various polymerization catalysts. Such polymerization catalysts include Ziegler-Natta catalysts and non-Ziegler-Natta catalysts, such as metallocenes and other transition metal catalysts which are typically employed in conjunction with one or more co-catalysts. The polymerization catalysts may be supported or unsupported.

The alpha olefin homopolymers or copolymers may be produced under various conditions in polymerization reactors which may be batch type reactors or continuous reactors. Continuous polymerization reactors typically take the form of loop-type reactors in which the monomer stream is continuously introduced and a polymer product is continuously withdrawn. For example, polymers such as polypropylene, polyethylene or ethylene-propylene copolymers involve the introduction of the monomer stream into the continuous loop-type reactor along with an appropriate catalyst system to produce the desired olefin homopolymer or copolymer. The resulting polymer is withdrawn from the loop-type reactor in the form of a “fluff” which is then processed to produce the polymer as a raw material in particulate form as pellets or granules. In the case of C₃₊ alpha olefins, such a propylene or substituted ethylenically unsaturated monomers such as styrene or vinyl chloride, the resulting polymer product may be characterized in terms of stereoregularity, such as in the case of, for example, isotactic polypropylene or syndiotactic polypropylene.

The structure of isotactic polypropylene can be described as one having the methyl groups attached to the tertiary carbon atoms of successive monomeric units falling on the same side of a hypothetical plane through the main chain of the polymer, e.g., the methyl groups are all above or below the plane. Using the Fischer projection formula, the stereochemical sequence of isotactic polypropylene is described as follows:

In Formula 1, each vertical segment indicates a methyl group on the same side of the polymer backbone. Another way of describing the structure is through the use of NMR. Bovey's NMR nomenclature for an isotactic pentad as shown above is . . . mmmm . . . with each “m” representing a “meso” dyad, or successive pairs of methyl groups on the same said of the plane of the polymer chain. As is known in the art, any deviation or inversion in the structure of the chain lowers the degree of isotacticity and crystallinity of the polymer.

In contrast to the isotactic structure, syndiotactic propylene polymers are those in which the methyl groups attached to the tertiary carbon atoms of successive monomeric units in the chain lie on alternate sides of the plane of the polymer. Syndiotactic polypropylene using the Fisher projection formula can be indicated by racemic dyads with the syndiotactic pentad rrrr shown as follows:

Here, the vertical segments again indicate methyl groups in the case of syndiotactic polypropylene, or other terminal groups, e.g. chloride, in the case of syndiotactic polyvinyl chloride, or phenyl groups in the case of syndiotactic polystyrene.

Other unsaturated hydrocarbons which can be polymerized or copolymerized with relatively short chain alpha olefins, such as ethylene and propylene include dienes, such as 1,3-butadiene or 1,4-hexadiene or acetylenically unsaturated compounds, such as methylacetylene.

SUMMARY OF THE INVENTION

In accordance with the present invention, there are provided catalyst compositions and processes for the polymerization of ethylenically unsaturated monomers to produce polymers, including copolymers or homopolymers. Monomers, which are polymerized or copolymerized in accordance with the present invention, include ethylene, C₃₊ alpha olefins and substituted vinyl compounds, such as styrene and vinyl chloride. A particularly preferred application of the invention is in the polymerization of propylene including the homopolymerization of propylene to produce polypropylene, preferably isotactic polypropylene and syndiotactic polypropylene having a high melting temperature, and the copolymerization of ethylene and a C₃₊ alpha olefin to produce an ethylene alpha olefin copolymer, specifically an ethylene-propylene copolymer.

In carrying out the present invention, there is provided an olefin polymerization catalyst characterized by the formula: B(FluL)MQ_(n)  (3) In formula (3), Flu is a fluorenyl group substituted at at least the 2,7- and 3,6-positions by hydrocarbyl groups, preferably relatively bulky hydrocarbyl groups. L is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group or a heteroorgano group, XR, in which X is a heteroatom from Group 15 or 16 of the Periodic Table of Elements, and R is an alkyl group, a cycloalkyl group or an aryl group. Preferably X is nitrogen, phosphorus, oxygen or sulfur. More preferably, X will take the form of nitrogen. R is an alkyl group or cycloalkyl group containing from 1 to 20 carbon atoms, or a mononuclear aromatic group which may be substituted or unsubstituted. Further, with respect to formula (3), B is a structural bridge extending between the groups L and Flu, which imparts stereorigidity to the ligand structure. Preferably, the bridge B is characterized by the formula ER¹R², in which E is a carbon, silicon or germanium atom, and R¹ and R² are each independently a hydrogen, a C₁-C₁₀ alkyl group, an aromatic group or a cycloalkyl group. Further, with respect to formula (3), M is a Group 4 or Group 5 transition metal, preferably titanium, zirconium or hafnium. Q is selected from the group consisting of chlorine, bromine, iodine, an alkyl group, an amino group, an aromatic group and mixtures thereof, n is 1 or 2 and will have a value of 2 where the transition metal is zirconium, hafnium or titanium.

In one embodiment of the invention, the fluorenyl group Flu is substituted with an aryl group at each of the 2- and 7-positions and with a lower molecular weight substituent at each of the 3- and 6-positions. More specifically, the fluorenyl group is substituted at the 2- and 7-positions with a phenyl or substituted phenyl group and at each of the 3- and 6-positions with a bulky hydrocarbyl group containing at least 4 carbon atoms. Preferably, the bulky hydrocarbyl group at the 3- and 6-positions is a tertiary butyl group.

In the embodiment of the invention in which the metallocene component is substituted at the 2- and 7-positions with an aryl group as described above and at the 3- and 6-positions with a tertiary butyl group, the metallocene component is characterized by the formula:

wherein Ar is a phenyl group or substituted phenyl group.

In a specific embodiment of the invention in which the ligand component L is a heteroorgano group, the metallocene component is characterized by the formula:

wherein Ar is a phenyl group or a substituted phenyl group, and R is an alkyl group having from 1 to 20 carbon atoms or an aryl group having from 6 to 20 carbon atoms.

In a further embodiment of the invention in which the metallocene component incorporates a cyclopentadienyl group, the metallocene is characterized by the formula:

In formula (6), Ar is a phenyl group or substituted phenyl group, R′ is a C₁-C₄ alkyl group or an aryl group, n is the number of substituents, from 0 to 4, E is a —C— group or an —Si— group, R¹ and R² are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group, M is titanium, zirconium or hafnium, and Q is chlorine, a methyl group or a phenyl group. Preferably, in formula (6), the cyclopentadienyl group is unsubstituted, disubstituted or tetra-substituted to provide a metallocene component which exhibits bilateral symmetry. In another embodiment of the invention, however, the cyclopentadienyl group is monosubstituted or trisubstituted to provide a metallocene component which exhibits non-bilateral symmetry.

In yet a further embodiment of the invention, the metallocene component incorporates a cyclopentadienyl group which is substituted with a methyl group and a tertiary butyl group to provide a metallocene component characterized by the formula:

In formula (7), Ar is a phenyl group or substituted phenyl group, E is a —C— group or an —Si— group, R¹ and R² are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group, M is titanium, zirconium or hafnium, and Q is chlorine, a methyl group or a phenyl group.

In yet a further embodiment of the invention, the metallocene component incorporates an unsubstituted cyclopentadienyl group and is characterized by the formula:

In formula (8), Ar is a phenyl group or substituted phenyl group, R¹ and R² are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group, E is a —C— group or an —Si— group, M is titanium, zirconium or hafnium, and Q is chlorine, a methyl group or a phenyl group.

Another embodiment of the invention involves a metallocene catalyst component which incorporates an indenyl group and is characterized by the formula:

In formula (9), Ar is a phenyl group or substituted phenyl group, Ind is an indenyl or substituted indenyl group, E is a —C— group or an —Si— group, each of R¹ and R² is independently a hydrogen, a C₁-C₁₀ alkyl group, a cycloalkyl group or an aryl group, M is titanium, zirconium or hafnium, and Q is chlorine, a methyl group or a phenyl group. In this aspect of the invention, the indenyl group may be a tetrahydroindenyl group which is substituted or unsubstituted.

In another aspect of the invention in which the secondary ligand component L is a fluorenyl group, the metallocene component is characterized by the formula:

In formula (10), Flu′ is a fluorenyl or a substituted fluorenyl group, E is a —C— group or an —Si— group, each of R¹ and R² is a C₁-C₄ alkyl group, M is titanium, zirconium or hafnium, and Q is chlorine, a methyl group or a phenyl group. Preferably, the fluorenyl group Flu′ in formula (10) is an unsubstituted fluorenyl group or a substituted fluorenyl group wherein the metallocene component exhibits bilateral symmetry.

In yet a further aspect of the invention, there is provided a process for the polymerization of one or more ethylenically unsaturated monomers to produce a corresponding homopolymer or copolymer. In carrying out the polymerization process, there is provided a metallocene catalyst component as characterized by the above formula (3). In addition to the metallocene catalyst component, there is provided an activating cocatalyst component. The catalyst component and the cocatalyst component are contacted in a polymerization reaction zone with an ethylenically unsaturated monomer under polymerization conditions to produce a polymer product which is then recovered from the reaction zone. Preferably, the activating co-catalyst comprises methylalumoxane (MAO) or tri-isobutylalumoxane (TIBAO) or mixtures thereof. Alternatively, the activating co-catalyst can take the form of a noncoordinating anionic type, such as triphenylcarbenium tetrakis(pentafluorophenyl)aluminate or triphenylcarbenium tetrakis(pentafluorophenyl)boronate. Preferably, the ethylenically unsaturated monomer is a C₃₊ alpha olefin. More specifically, the alpha olefin is propylene and the polymerization reaction is carried out to produce syndiotactic or isotactic polypropylene.

In a preferred embodiment of the invention, the metallocene component incorporates a cyclopentadienyl group and is characterized by the formula:

In formula (11), Ar is a phenyl group or substituted phenyl group, R¹ and R² are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group, R′ is a C₁-C₄ alkyl group or an aryl group, n is a number from 0 to 4, E is a —C— group or an —Si— group, each of R₁ and R₂ is a C₁-C₄ alkyl group, M is titanium, zirconium or hafnium, and Q is chlorine, a methyl group, a phenyl group, or a substituted phenyl or benzyl group. In one aspect of this embodiment of the invention, the metallocene component exhibits bilateral symmetry and the polymer product is syndiotactic polypropylene. In another aspect, the metallocene does not exhibit bilateral symmetry and the polymer product is isotactic polypropylene. In a specific embodiment of the process, the metallocene component incorporates an unsubstituted cyclopentadienyl group and is characterized by the formula:

to produce a syndiotactic polypropylene having a melting temperature higher than 150° C. and a crystallization temperature of more than 95° C. Preferably, the syndiotactic polypropylene has a melting temperature greater than 170° C.

DETAILED DESCRIPTION OF INVENTION

The present invention involves bridged transition metal catalysts having metallocene ligand structures incorporating tetra-substituted fluorenyl groups and their use in the polymerization of olefins. Specific olefins which may be polymerized, either through homopolymerization or copolymerization include ethylene, propylene, butylene, as well as monoaromatic or substituted vinyl compounds as described previously. The bridged catalyst components of the present invention incorporate transition metals from Groups 4 or 5 of the Periodic Table of Elements (new notation) and more particularly, transition metals from Group 4 of the Periodic Table of Elements. Preferred transition metals for use in the catalyst components of the present invention are titanium, zirconium and hafnium, with zirconium being particularly preferred.

The catalyst components of the present invention incorporate a primary fluorenyl group that is tetra-substituted fluorenyl group which is bridged to a secondary ligand structure which is a substituted or unsubstituted cyclopentadienyl, indenyl or fluorenyl group or a heteroorgano group. The tetra-substituted fluorenyl groups are symmetrical with respect to a plane of symmetry through the bridge and the transition metal. Preferably, the substituents at the 2,7 positions are bulkier than the substituents at the 3,6 positions. However, a reverse relationship of substitution may be employed in some instances. In this case, the primary fluorenyl group may be substituted at the 2- and 7-positions with a C₁-C₃ alkyl group and at the 3- and 6-positions with a bulky hydrocarbyl group containing at least 4 carbon atoms. More specifically, the catalyst components of the present invention comprise metallocene ligand structures which incorporate tetra-substituted fluorenyl groups substituted at at least the 2,7 and 3,6 positions which are bridged to substituted or unsubstituted cyclopentadienyl, indenyl, fluorenyl or heteroorgano groups and which are characterized in terms of symmetry (or asymmetry) with reference to a plane of symmetry extending through the bridge and the transition metal.

The following diagrams indicate metallocene ligand structures (and the numbering schemes for such structures) which may be employed in carrying out the present invention. Diagram (13) indicates a cyclopentadienyl-fluorenyl ligand structure, diagram (14) an indenyl-fluorenyl ligand structure, diagram (15) a heteroatom (XR)-fluorenyl ligand structure, and diagram (16) a fluorenyl-fluorenyl ligand structure.

The numbering schemes used to indicate the position of substituents on the various ligand structures are indicated on diagrams (13)-(16). With respect to structure (14), while not shown, the indenyl moiety may take the form of 4,5,6,7-tetrahydro indenyl as well as the more common unhydrogenated indenyl group. For each of diagrams (13)-(16), the metallocene ligand structures may be characterized in terms of a plane of symmetry extending perpendicular to the plane of the paper through the bridge group B and the transition metal (not shown) in diagrams (13)-(16) which would project upwardly from the plane of the paper.

As described with respect to various examples given below and with respect, for example, to diagram (13), the cyclopentadienyl group may be monosubstituted and the fluorenyl group may be symmetrically substituted at the 2,7 and 3,6 positions. If there are no other substituents or if the fluorenyl group is otherwise symmetrically substituted, the 3-position is equivalent to the 4-position on the cyclopentadienyl group and this relationship may be expressed by the positional expression 3(4).

The catalysts of the present invention can be advantageously used in propylene polymerization to produce syndiotactic or isotactic polypropylenes with high yields, having high molecular weights, high tacticities and high melt temperatures. Desired features of the catalysts of the present invention are due to a unique combination of structural parameters of the catalysts and substitutions of the cyclopentadienyl and fluorenyl rings. In addition, the catalysts of the present invention can be used in copolymerization of propylene with olefins, e.g. ethylene to yield random or impact copolymers.

Ligand structures suitable for use in carrying out the present invention which can be employed to produce isotactic polypropylene include, with reference to diagram (13), 3-tertiary butyl, 5-methyl cyclopentadienyl, 2,7-ditertiary butyl, 4-phenyl fluorene, the same ligand structure except with substitution on the fluorenyl structure at the 5-position and the same ligand structure with substitution at the 4- or 5-positions by a 4-tertiary butyl phenyl group. In other words, the phenyl group is substituted by a tertiary butyl group at the directly distal position with respect to the substitution of the phenyl group on the fluorenyl group.

Other suitable ligand structures which can be employed to produce isotactic polypropylene include ligand structures such as described above, except the cyclopentadienyl group is mono-substituted at the 3-position with a tertiary butyl group. The fluorenyl group is substituted as before at the 2- and 7-positions with the tertiary butyl groups and at the 4-position with a phenyl group or a 4-tertiary butyl phenyl group.

Similarly substituted ligand structures may be employed in accordance with the present invention incorporating a bis-indenyl fluorenyl ligand structure exemplified by diagram (14). Typically, because of the unbalanced characteristic of the indenyl structure, further substitution of the indenyl (or the 4,5,6,7-tetrahyrdo indenyl) group will not be employed. The fluorenyl ligand component may be substituted as described previously, thus, it may be substituted at the 4-position or di-substituted at the 4- and 5-positions with bulky groups such as tertiary butyl and phenyl groups. Also, the fluorenyl ligand structure may be substituted at one of the 4- and 5-positions and disubstituted at the 2- and 7-positions with substituent groups which are less bulky than the substituents on the 4- or 5-positions.

The heteroatom ligand structure depicted in diagram (15) may be substituted on the fluorenyl group similarly as described above with respect to diagrams (13) and (14). Thus, for example, the fluorenyl group may be substituted at the 2- and 7-positions with tertiary butyl groups and substituted at the 4-position with a substituted or unsubstituted phenyl group. Alternatively, the fluorenyl group may be unsubstituted at the 2- and 7-positions and substituted at the 4-position with an isopropyl group, a tert-butyl group, a phenyl group or a substituted phenyl group.

In employing the catalyst components of the present invention in polymerization procedures, they are used in conjunction with an activating co-catalyst. Suitable activating co-catalysts may take the form of co-catalysts such are commonly employed in metallocene-catalyzed polymerization reactions. Thus, the activating co-catalyst may take the form of an aluminum co-catalyst. Alumoxane co-catalysts are also referred to as aluminoxane or polyhydrocarbyl aluminum oxides. Such compounds include oligomeric or polymeric compounds having repeating units of the formula:

where R is an alkyl group generally having 1 to 5 carbon atoms. Alumoxanes are well known in the art and are generally prepared by reacting an organo-aluminum compound with water, although other synthetic routes are known to those skilled in the art. Alumoxanes may be either linear polymers or they may be cyclic, as disclosed for example in U.S. Pat. No. 4,404,344. Thus, alumoxane is an oligomeric or polymeric aluminum oxy compound containing chains of alternating aluminum and oxygen atoms whereby the aluminum carries a substituent, preferably an alkyl group. The structure of linear and cyclic alumoxanes is generally believed to be represented by the general formula —(Al(R)—O—)-m for a cyclic alumoxane, and R²Al—O—(Al(R)—O)_(m)—AlR² for a linear compound wherein R independently each occurrence is a C₁-C₁₀ hydrocarbyl, preferably alkyl or halide and m is an integer ranging from 1 to about 50, preferably at least about 4. Alumoxanes also exist in the configuration of cage or cluster compounds. Alumoxanes are typically the reaction products of water and an aluminum alkyl, which in addition to an alkyl group may contain halide or alkoxide groups. Reacting several different aluminum alkyl compounds, such as, for example, trimethylaluminum and tri-isobutylaluminum, with water yields so-called modified or mixed alumoxanes. Preferred alumoxanes are methylalumoxane and methylalumoxane modified with minor amounts of other higher alkyl groups such as isobutyl. Alumoxanes generally contain minor to substantial amounts of the starting aluminum alkyl compounds. The preferred co-catalyst, prepared either from trimethylaluminum or tri-isobutylaluminum, is sometimes referred to as poly (methylaluminum oxide) and poly (isobutylaluminum oxide), respectively.

The alkyl alumoxane co-catalyst and transition metal catalyst component are employed in any suitable amounts to provide an olefin polymerization catalyst. Suitable aluminum transition metal mole ratios are within the range of 10:1 to 20,000:1 and preferably within the range of 100:1 to 5,000:1. Normally, the transition metal catalyst component and the alumoxane, or other activating co-catalyst as described below, are mixed prior to introduction in the polymerization reactor in a mode of operation such as described in U.S. Pat. No. 4,767,735 to Ewen et al. The polymerization process may be carried out in either a batch-type, continuous or semi-continuous procedure, but preferably polymerization of the olefin monomer (or monomers) will be carried out in a loop type reactor of the type disclosed in the aforementioned U.S. Pat. No. 4,767,735. Typical loop type reactors include single loop reactors or so-called double loop reactors in which the polymerization procedure is carried in two sequentially connected loop reactors. As described in the Ewen et al. patent, when the catalyst components are formulated together, they may be supplied to a linear tubular pre-polymerization reactor where they are contacted for a relatively short time with the pre-polymerization monomer (or monomers) prior to being introduced into the main loop type reactors. Suitable contact times for mixtures of the various catalyst components prior to introduction into the main reactor may be within the range of a few seconds to 2 days. For a further description of suitable continuous polymerization processes which may be employed in carrying out the present invention, reference is made to the aforementioned U.S. Pat. No. 4,767,735, the entire disclosure of which is incorporated herein by reference.

Other suitable activating co-catalysts which can be used in carrying out the invention include those catalysts which function to form a catalyst cation with an anion comprising one or more boron atoms. By way of example, the activating co-catalyst may take the form of triphenylcarbenium tetrakis(pentafluorophenyl) boronate as disclosed in U.S. Pat. No. 5,155,080 to Elder et al. As described there, the activating co-catalyst produces an anion which functions as a stabilizing anion in a transition metal catalyst system. Suitable noncoordinating anions include [W(PhF₅)]⁻, [Mo(PhF₅)]⁻ (wherein PhF₅ is pentafluorophenyl), [ClO₄]⁻, [S₂O₆]⁻, [PF₆]⁻, [SbR₆]⁻, [AlR₄]⁻ (wherein each R is independently Cl, a C₁-C₅ alkyl group preferably a methyl group, an aryl group, e.g. a phenyl or substituted phenyl group, or a fluorinated aryl group). Following the procedure described in the Elder et al. patent, triphenylcarbenium tetrakis(pentafluorophenyl) boronate may be reacted with pyridinyl-linked bis-amino ligand of the present invention in a solvent, such as toluene, to produce a coordinating cationic-anionic complex. For a further description of such activating co-catalyst, reference is made to the aforementioned U.S. Pat. No. 5,155,080, the entire disclosure of which is incorporated herein by reference.

In addition to the use of an activating co-catalyst, the polymerization reaction may be carried out in the presence of a scavenging agent or polymerization co-catalyst which is added to the polymerization reactor along with the catalyst component and activating co-catalyst. These scavengers can be generally characterized as organometallic compounds of metals of Groups 1A, 2A, and 3B of the Periodic Table of Elements. As a practical matter, organoaluminum compounds are normally used as co-catalysts in polymerization reactions. Specific examples include triethylaluminum, tri-isobutylaluminum, diethylaluminum chloride, diethylaluminum hydride and the like. Co-catalysts normally employed in the invention include methylalumoxane (MAO), triethylaluminum (TEAL) and tri-isobutylaluminum (TIBAL).

The bridged fluorenyl ligand structures and the corresponding transition metal catalyst components can be prepared by any suitable techniques. Typically, for methylene bridged cyclopentadienyl fluorenyl ligand structures, the fluorenyl group is treated with methyl lithium to result in a fluorenyl group substituted with lithium in the 9-position and this is then reacted with a 6,6-substituted fulvene. For example, 6,6-dimethyl fulvene may be employed to produce the isopropylidene cyclopentadienyl substituted fluorenyl ligand structure. For a ligand structure in which the bridge group incorporates a germanium or silicon atom, the lithiumated fluorenyl group is reacted, for example, with diphenylsilyl dichloride to produce the diphenylsilyl chloride substituent at the 9-position on the fluorenyl group. This component is then reacted with the lithiumated cyclopentadienyl or substituted cyclopentadienyl to produce the bridge. The ligand structure is then treated with methyl lithium, followed by reaction with the appropriate transition metal, chlorine, e.g. zirconium tetrachloride, to produce the corresponding metallocene dichloride.

The catalyst components employed in the present invention can be prepared by techniques, which include procedures well-known in the art with appropriate modification of the fluorenyl ligand component to incorporate a 2,7,3,6-tetra-substituted fluorene. For example, as described below, 6,6-dimethyl fulvene can be employed in conjunction with 2,7,3,6 symmetrically substituted fluorene in order to produce the corresponding methylene-bridged cyclopentadienyl 2,7,3,6-tetra-substituted fluorene. The fluorenyl-fluorenyl ligand structures employed in the present invention can be synthesized using a procedure such as disclosed in U.S. Pat. No. 6,313,242 to Reddy to form bis-fluorenyl ligands, again with the qualification that a symmetrical ligand structure rather than the staggered ligand structure of the type disclosed in Reddy will be produced. Similarly, a bridged fluorenyl heteroatom ligand structure of the type characterized by formula 10 above can be produced by preparation of a substituted fluorene with dimethyldichlorosilane, followed by reaction with a tertiary butyllithiumamide to produce the bridged fluorenyl amine structure. Again, the above procedure would be followed, but with the modification to employ, for example, 2,7-diphenyl,3,6-ditertiary butyl fluorene rather than the 3,6-ditertiary butyl fluorene disclosed in the Reddy patent. The various procedures which can be used in the synthesis of the metallocene components of the present invention are illustrated by the synthesis procedures described below.

Specific metallocenes embodying the present invention are illustrated by the following structural formulas in which the isopropylidene bridge group is illustrated by

and a tertiary butyl group is indicated by

.

1. Synthesis of Catalysts

2,7-Dibromo-3,6-di-t-butyl-fluorene was synthesized by the reaction of 3,6-di-t-butyl-fluorene with N-bromo succinimide in propylene carbonate solution in 82% yield in accordance with the following reaction and used as a starting material for the synthesis of 2,7-di-aryl-3,6-di-tert-butyl-fluorenes for catalysts M1-M15:

The coupling reaction of 2,7-dibromo-3,6-di-t-butyl-fluorene with phenyl boronic acid provided 2,7-phenyl-3,6-di-t-butyl-fluorene in 90% yield in accordance with the following reaction:

EXAMPLE 1 Synthesis of 2,7-Dibromo-3,6-di-t-butyl-fluorene

To a solution of 3,6-di-t-butylfluorene (2.10 g, 7.55 mmol) in propylene carbonate (60 ml) was added 2.70 g of N-bromosuccinimide. The reaction mixture was stirred for 6 hours at 70-75° C. The mixture was poured into water and the precipitated solid was filtered, washed with water and dried to produce a yield of 2.71 g (82%). ¹H NMR (CDCl₃): δ 7.80 and 7.72 (each s, 2H, 1,8- and 4,5-H (Flu), 3.74 (s, 2H, H9), 1.59 (s, 18H, t-Bu).

The coupling reaction of 2,7-dibromo-3,6-di-t-butyl-fluorene with aryl boronic acid produced 2,7-aryl-3,6-di-t-butyl-fluorene in an 85-95% yield in accordance with the following reaction:

EXAMPLE 2 Synthesis of 2,7-Diphenyl-3,6-di-t-butyl-fluorene

To a mixture of 2,7-dibromo-3,6-di-t-butylfluorene (0.96 g, 2.20 mmol) and Pd(PPh₃)₄ (260 mg, 0.22 mmol) in toluene (50 ml) was added a solution of phenylboronic acid (0.81 g, 6.63 mmol) in EtOH (10 ml) and a solution of Na₂CO₃ (1.5 g) in water (10 ml). The reaction mixture was stirred for 6 hours under reflux. The reaction mixture was quenched with water, extracted with ether, dried over MgSO₄, and evaporated under vacuum to afford the residue which was purified by column chromatography (silica gel, hexane/CH₂Cl₂=5/1) to produce 2,7-diphenyl-3,6-di-t-butyl-fluorene (0.85 g, ˜90%). ¹H NMR (CDCl₃): δ 7.96 and 7.15 (each s, 2H, 1,8- and 4,5-H (Flu), 7.33 (m, 10H, Ph), 3.77 (s, 2H, H9), 1.27 (s, 18H, t-Bu).

EXAMPLE 3 Synthesis of 2,7-Di(4-tert-butyl-phenyl)-3,6-di-t-butyl-fluorene

The same procedure as in Example 2 was used except 4-tert-butyl-phenyl-boronic acid was used in place of phenylboronic acid. The yield was 92%.

The following Examples 4 and 5 illustrate the preparation of 2,7-dimethyl-3,6-di-tert-butyl-fluorene.

EXAMPLE 4 Synthesis of 2,7-dichloromethane-3,6-di-tert-butyl-fluorene

To a solution of 3,6-di-t-butylfluorene (2.00 g, 7.19 mmol) and chloromethyl methyl ether (2.5 ml) in CS₂ (15 ml) was added at 0° C. a solution of TiCl₄ (0.4 ml) in CS₂ (5 ml). The reaction mixture was stirred for 3 hours at room temperature. The mixture was poured into ice water and extracted with ether. The ether extract was dried over sodium sulfate and evaporated under vacuum to leave a residue, which was purified by column chromatography (hexane/CH₂Cl₂=10/1) and crystallization from hot heptanes. The product provided 2-chloromethyl-3,6-di-t-butylfluorene (yield 0.75 g). ¹H NMR (CDCl₃): δ 7.80 and 7.78 (each d, 1H, 4,5-H), 7.47 (d, 1H, J=8.1 Hz, H8), 7.34 (dd, 1H, J=8.1 Hz, J=1.5 Hz, H7), 7.31 (d, 1H, 1H, J=1.5 Hz, H1), 4.72 (s, 2H, CH₂Cl), 3.87 (s, 2H, H9), 1.41 (s, 18H, t-Bu) and 2,7-dichloromethyl-3,6-di-t-butylfluorene (yield 0.63 g). ¹H NMR (CDCl₃): δ 7.87 (br s, 2H, 4,5-H), 7.34 (br s, 2H, 1,8-H), 4.75 (s, 4H, CH₂Cl), 3.95 (s, 2H, H9), 1.42 (s, 18H, t-Bu) as indicated by the following reaction:

EXAMPLE 5 Reduction of 2,7-dichloromethane-3,6-di-tert-butyl-fluorene

To a solution of 2,7-di-chloromethyl-3,6-di-t-butylfluorene (0.75 g) in THF (15 ml) was added a small portion of LiAlH₄ (0.25 g) under stirring. The mixture was refluxed for 5 hours. The reaction was quenched with water and NaOH, and extracted with ether. The ether solution was evaporated under vacuum to produce a white solid with a yield of 0.69 g.

Examples 6 and 7 illustrate the synthesis of 2,2-[(cyclopentadienyl)-(2,7-di-phenyl-3,6-di-tert-butylfluorenyl)]-isopropylidene zirconium dichloride (catalyst component M1).

EXAMPLE 6 2,2-[(Cyclopentadienyl)-[(2,7-di-phenyl-3,6-di-tert-butylfluorenyl)]-propane

Butyllithium (1.5 ml, 1.6M in hexane, 2.40 mmol) was added to 2,7-diphenyl-3,6-di-t-butyl-fluorene (0.95 g, 2.20 mmol) in THF (20 ml) at −78° C. The reaction mixture was allowed to warm to room temperature and stirred for 2.5 hours. The solvent was removed under vacuum. Ether (5 ml) was added and removed under vacuum. Ether (25 ml) was added and 6,6′-dimethylfulvene (0.23 g, 2.43 mmol) in ether (5 ml) was added to the reaction mixture at 0° C. The reaction was stirred at room temperature for 5 days. The reaction mixture was quenched with water, extracted with ether, dried over MgSO₄, and evaporated under vacuum to afford the residue which was purified by column chromatography (silica gel, hexane/CH₂Cl₂=5/1) and crystallized from hot hexane. The yield was 0.40 g, 34%. ¹H NMR (CDCl₃): δ 7.91 and 7.30 (each s, 2H, 1,8- and 4,5-H (Flu), 7.35 (m, 10H, Ph), 6.76, 6.40 (m, 3H, Cp), 4.04 and 4.02 (s, 2H, H9), 3.00 and 2.78 (br s, 2H, CH2 Cp), 1.31 (s, 18H, t-Bu), 1.11 and 1.09 (s, 6H, Me). ¹H NMR (CD₂Cl₂): δ 7.91 and 7.29 (each s, 2H, 1,8- and 4,5-H (Flu), 7.2-7.4 (m, 10H, Ph), 6.8-6.7, 6.40 (m, 3H, Cp), 4.02 (brs, 2H, H9), 3.00 and 2.78 (br s, 2H, CH2 Cp), 1.28 (s, 18H, t-Bu), 1.07 and 1.04 (s, 6H, Me). HPLC: 10.38 and 10.65 min.

EXAMPLE 7 2,2-[(Cyclopentadienyl)-(2,7-di-phenyl-3,6-di-tert-butylfluorenyl)]-propane zirconium dichloride (catalyst M1)

Butyllithium (1.0 ml, 1.6M in Et₂₀, 1.60 mmol) was added to 2,2-[(cyclopentadienyl)-[(2,7-d]-phenyl-3,6-di-tert-butylfluorenyl)]-propane (0.39 g, 0.73 mmol) in THF (10 ml) at −78° C. The reaction mixture was allowed to warm to room temperature and stirred for 2.5 hours. The solvent was evaporated under vacuum. Ether (5 ml) was added and removed under vacuum. ZrCl₄ (0.170 g, 0.76 mmol) was added. at −78°. Ether (10 ml) was added to reaction mixture. The reaction mixture was allowed to warm to room temperature and stirred for 5 hours. The solvent was removed under vacuum to afford an orange solid, which was tested in propylene polymerization without purification. ¹H NMR (C₆D₆): δ 8.14 (s, 2H, Flu-1,8), 7.4-7.2 (m, 12H, Ph, Flu-5,6), 6.04 and 5.69 (each m, 2H, Cp), 1.33 (s, 18H, t-Bu).

Examples 8-10 illustrate the synthesis of (4-tert-butyl-phenyl) [(cyclopentadienyl)(2,7-d]-phenyl)-(3,6-di-tert-butyl-fluorenyl)]methane zirconium dichloride (catalyst M12).

EXAMPLE 8 6-(4-tetr-butyl-phenyl)-5-methyl-3-tert-butyl-fulvene

To a solution of methyl-tert-butylcyclopentadiene (4.42 g, 32.5 mmol) and 4-t-butyl-benzaldehyde (5.15 g) in absolute ethanol (30 ml) was added a small portions of sodium methoxide (4.0 g) under stirring. The mixture was stirred for 2 hours. The reaction was quenched with water and extracted with ether. The ether solution was evaporated under vacuum to give an orange liquid, which was purified by column chromatography (silica gel, hexane/CH₂Cl₂=8/1), providing a yield of 7.0 g. ¹H NMR (CDCl₃): δ 7.55 (m, 2H, Ph), 7.48 (m, 2H, Ph), 7.02 (s, 1H, H—CPh), (m, 1H, H-6), 6.27 and 6.22 (br s, 2H, H-Cp), 2.18 (s, 3H, Me), 1.39 and 1.23 earh (s, 9H, t-Bu).

EXAMPLE 9 (4-tert-butyl-phenyl)[(cyclopentadienyl)-[(2,7-di-phenyl-3,6-di-tert-butylfluorenyl)]-methane

Butyllithium (1.5 ml, 1.6M in hexane, 2.40 mmol) was added to 2,7-diphenyl-3,6-di-t-butyl-fluorene (1.02 g, 2.33 mmol) in ether (20 ml) at −78° C. The reaction mixture was allowed to warm to room temperature and stirred for 2.5 hours. 6-(4-tert-Butyl-phenyl)-fulvene (0.49 g, 2.33 mmol) in ether (5 ml) was added to the reaction mixture at −20° C. The reaction was stirred at room temperature for 2 hours. The reaction mixture was quenched with water, extracted with ether, dried over MgSO₄, and evaporated under vacuum to afford the residue, which was washed with hot ethanol.

EXAMPLE 10 (4-tert-Butyl-phenyl)[(cyclopentadienyl)(2,7-di-phenyl)-(3,6-di-tert-butyl-fluorenyl)]methane zirconium dichloride (catalyst M12)

Butyllithium (1.3 ml, 1.6M, 2.08 mmol) was added to (4-tert-butyl-phenyl)[(cyclopentadienyl)(2,7-d]-phenyl)-(3,6-di-tert-butyl-fluorenyl)]methane (0.61 g, 0.95 mmol) in ether (10 ml) at −78° C. The reaction mixture was allowed to heat to room temperature and the reaction was continued for 2.5 hours. The solvent was removed under vacuum. ZrCl₄ (220 mg) was added to the reaction mixture. Toluene (15 ml) was added at −20° C. and the reaction was stirred at room temperature for night. The solvent was removed under vacuum.

Catalysts M2-M11 and M13-M18 can be prepared as described in the foregoing Examples through the use of the corresponding 2,7-di-substituted-3,6-tert-butyl-fluorene and fulvene.

EXAMPLES 11-17 Homogeneous Polymerization with Catalyst M1

The polymerization was conducted in bulk propylene at 40, 60 and 70° C. in a 4 L reactor using the crude catalyst from Reaction 21 without purification. The polymerization behavior for the catalyst is set forth in Tables 1 through 3. The catalyst produced a polymer with activity of 30,000 gPP/gcat/h at 60° C. without hydrogen. In the presence of hydrogen (60 ppm) the activity increased up to 142,400 gPP/gcat/h. The catalyst produced syndiotactic polypropylene with pentad rrrr values of 85-92% (Table 4), melting temperature of 149-163° C. and molecular weight of 130,000 (Table 3). A broader molecular weight distribution (D) was also observed due to the presence of a low molecular weight fraction, a content of which could be decreased by fraction extraction of the polymer. Fraction extraction of the sample with hot hexane for 3 hours provided a polymer with a narrow molecular weight distribution (D=1.9), melting temperature of 153° C. and tacticity of 92% of rrrr pentad. TABLE 1 Bulk Propylene Polymerization with Unsupported Catalyst M1 Catalyst T, Time, H₂, Activity, MFR, Example mg ° C. min ppm PP, g gPP/g cat/h dg/min 11^(a) 20 −10 180 0 2.0 12 7.0 40 60 0 42 6,000 13 10 60 30 0 150 30,000 3.6 14^(b) 15^(c) 16 5.5 60 10 60 130 142,390 4.3 17 4.3 70 30 0 10 4,650 ^(a)Polymerization at 1 atmosphere of propylene in toluene ^(b)Crystallized fraction from xylene of sample 13 ^(c)Heptane extraction of sample 14

TABLE 2 DSC Data of Polypropylene T melt, T cryst, Delta H Delta H Example ° C. ° C. melt, J/g recryst, J/g 11 163.0 109.0 29.6 −39.3 12 160.4 98.6 37.0 −97.9 13 149.4 89.6 46.3 −59.6 14 15 152.7 97.6 44.7 −49.0 16 154.4 109.6 40.8 −109.6 17 146.0 101.0 29.2 −48.9

TABLE 3 GPC Data of Polypropylene Example Mn Mw Mz D D′ 11 7,909 222,922 1211,160 28^(a)   5.4 12 6,394 169,439 510,047 26.5^(a ) 3.0 13 31,719 161,604 324,372 5.1 2.0 14 45,600 166,100 338,760 3.6 2.0 15 96,447 186,871 335,371 1.9 1.8 16 27,298 149,743 285,755 5.5 1.9 17 26,940 129,260 254,190 4.8 2.0 ^(a)bimodal

TABLE 4 Pentad Distributions for Syndiotactic Polypropylene Example Example Example Example Example 12 13 14 16 17 mmmm % 2.1 0.3 0.3 0.4 0.4 mmmr 4.4 0.6 0.0 0.8 0.5 rmmr 2.5 0.8 0.6 1.0 1.0 mmrr 3.3 1.3 0.9 1.4 1.5 xmrx 9.2 3.0 1.5 3.2 4.0 mrmr 5.8 1.4 0.0 1.4 0.8 rrrr 65.2 87.5 92.0 86.3 84.9 rrrm 4.0 3.7 3.8 4.1 5.7 mrrm 3.6 1.4 0.9 1.3 1.2 % meso 18.2 4.6 2.1 5.3 5.1 % racemic 81.8 95.4 97.9 94.7 94.9 % error 7.1 2.3 1.4 2.6 3.0 def/1000° C. 90.9 22.8 10.4 26.5 25.3

EXAMPLES 18-25 Homogeneous Polymerization with Catalyst M12

The polymerizations in Examples 18-20 were conducted in bulk propylene using 10X-Multi-Clave reactor from Autoclave Engineers in 5 ml of bulk propylene in 30 ml glass vessels. The catalyst was activated with MAO (Zr/Al=1/1000-2000) prior to polymerization. TABLE 5 Propylene polymerization with Catalyst M12 in 10X Multi-Clave reactors (bulk propylene, homogeneous, 60° C., 30 min, no H₂) Catalyst Activity, Tmelt, Tcryst, Mw/ Mw/ Mz/ Example (mg) T°, C Polymer, g g/g//h ° C. ° C. 1000 Mn Mw 18 0.15 50-60 1 13,300 158.7 96.3 206.7 2.6 1.9 19 0.45 40-50 3.6 10,526 161.9 99.0 278.8 2.9 1.8 20 0.9 20 5.7 6,333 160.0 96.3 300.0 2.6 1.8 a The highest melting peak

EXAMPLE 21 Propylene Polymerization Under 1 atm with Catalyst M12

The propylene polymerization in Example 21 was conducted with 1.3 mg of catalyst M12, activated with 2 ml of 30% MAO, using the glass reactor under 1 atm of propylene in toluene solution at −10° C. for 3 hours. 1.6 g of polypropylene was isolated. Tmelt=171° C., T cryst=112.3° C., Mw=446,200, Mw/Mn=3.0, Mz/Mw=1.9. TABLE 6 Tacticity of polypropylene samples Example Example Example TACTICITY, % 20 19 21 mmmm 0.1 0.2 2.5 mmmr 0.3 0.0 1.1 rmmr 0.3 0.2 0.2 mmrr 0.6 0.5 0.4 xmrx 0.8 0.4 1.0 mrmr 0.2 0.0 0.1 rrrr 89.7 94.6 90.7 rrrm 6.1 3.2 3.0 mrrm 1.9 0.9 1.1 % meso 1.5 0.8 4.5 % racemic 98.5 99.2 95.5 % error 0.7 0.3 0.7 def/1000 C. 7.4 4.2 22.3

The polymerizations in Examples 22-25 were conducted in bulk propylene using a 2 L Zipper-Clave reactor from Autoclave Engineers. The reactor was charged with 300 g of bulk propylene prior to polymerization. The catalyst was activated with MAO (Zr/Al=1/1000-2000) prior to polymerization. TABLE 7 Bulk propylene polymerization with Catalyst M12 under homogeneous condition Catalyst T, H2, Activity, Tm, MF, Mw/ Mw/ Mz/ % Tol Example (mg) ° C. ppm Polymer, g g/g//h ° C. g/10 min 1000 Mn Mw Sol 22 0.3 50 30 56 373,333 159.7 1.0 219.8 2.6 1.8 0.5 23 0.5 60 60 65 260,000 157.7 1.9 173.4 2.2 1.8 0.9 24 0.2 60 30 53 530,000 155.7 1.5 176.9 2.2 1.8 25 1.5 70 60 146 195,000 153.4 3.2 154.0 2.5 1.9 0.6 As can be seen from Examples 18-25, catalyst M12 produced syndiotactic polypropylene with pentad rrrr values of 88-95%, melting temperatures of 153-171° C., molecular weights of 154,000-300,000 at activities up to 530,000 gPP/Gcat/h.

EXAMPLES 26-29 Propylene Polymerization with Supported Catalyst M1

The catalyst M1 was supported on a silica support available from Asahi Glass Co., Ltd. under the designation H-121. The silica support had an average particle size of 12 microns. The catalyst supported on the silica with a 2 wt. % loading was tested at 60° C. for 1 hour in a 4 L reactor. The polymerization behavior for the unsupported catalyst is set forth in Tables 8 and 9. The hydrogen response of the supported catalyst was tested. The hydrogen response of the supported catalyst showed that the catalyst activity increased as the hydrogen levels increased (Table 8). The melting temperature of polymers produced in the presence of hydrogen was around 136-137° C. and is slightly dependent on hydrogen concentration. The molecular weight of the polymers showed a range of 99,000 for hydrogen levels of 0-75 ppm. In addition, the melt flow rate slightly increased from 31-44 g/10 min. with increasing the hydrogen concentration from 40 to 75 ppm. The supported catalyst produced a polymer with a narrow molecular weight distribution (D=2.1-2.6). Polymer produced using the supported catalyst showed good stereoregularity (% rrrr=82-83 in the presence of hydrogen) (Table 9). TABLE 8 Polymerization Test Results for Supported Catalyst M1 Cat T, Time, H2, Activity MFR, Example mg ° C. min ppm PP, g gPP/g cat/h dg/min T melt, ° C. Mn Mw Mz D D′ 26 40* 60 60 0 4 100 127.7 38,967 99,373 166,385 2.6 1.7 27 40* 60 60 40 25 625 31 137.2/120.9 37,442 78,308 129,672 2.1 1.7 28 20* 60 60 60 13 650 39 136.0/119.6 35,644 82,217 140,208 2.3 1.7 29 40* 60 60 75 31 775 44 137.2/120.9 37,442 78,308 129,672 2.1 1.7

TABLE 9 Pentad Distributions for Syndiotactic Polypropylene Produced with Supported Catalyst Example Example 26 27 Example 28 Example 29 mmmm % 0.4 0.1 0.2 0.0 mmmr 0.3 0.2 0.2 0.2 rmmr 1.2 1.3 1.3 1.3 mmrr 2.1 2.1 2.1 2.2 xmrx 4.6 4.5 4.6 4.3 mrmr 0.4 0.4 0.2 0.3 rrrr 77.9 82.3 82.6 83.2 rrrm 8.1 7.8 7.9 7.4 mrrm 5.0 1.2 1.1 1.1 % meso 5.4 5.2 5.1 4.9 % racemic 94.6 94.8 94.9 95.1 % error 3.5 3.5 3.6 3.4 def/1000° C. 17.5 17.7 17.8 17.2

EXAMPLES 30-33 Propylene Polymerization with Supported Catalyst M12

The catalyst M12 was supported on silica supports available from Asahi Glass Co., Ltd. under the designation H-121 and G952. The catalyst supported on the silica with a 2 wt. % loading was tested at 60° C. for 30 minutes in 500 ml stainless reactor. The results in terms of polymerization parameters and polymer properties are shown in Tables 10 and 11. TABLE 10 Propylene polymerization with Supported Catalyst M12 H2, Activity, Tm, Tc, Mw/ Mw/ Mz/ Entry # Support Run # ppm Polymer, g g/g/cat/h ° C. ° C. 1000 Mn Mw 30 G952 1137- 10 6.1 610 142.0/ 89.3 105 2.5 1.8 099-R3 128.3 31 G952 1137- 60 7 700 142.4 89.3 96 2.8 1.9 099-R4 32 H-121-C 1137- 10 1.8 180 139.0 87.3 105 2.7 1.8 099-R5 33 H-121-C 1137- 60 3 300 141.4 86.6 96 2.5 1.8 099-R6

TABLE 11 Tacticity of polypropylene produced with supported Catalyst M12 Example Example 31 33 mmmm, % 0.4 0.4 mmmr 0.3 0.3 rmmr 0.8 0.8 mmrr 1.9 1.8 xmrx 3.3 3.4 mrmr 0.5 0.0 rrrr 90.4 83.2 rrrm 1.9 8.1 mrrm 0.7 1.8 % meso 4.2 4.2 % racemic 95.8 95.8 % error 2.4 2.6 def/1000° C. 21.2 20.9

Having described specific embodiments of the present invention, it will be understood that modifications thereof may be suggested to those skilled in the art, and it is intended to cover all such modifications as fall within the scope of the appended claims. 

1. A metallocene component for an olefin polymerization catalyst characterized by the formula: B(FluL)MQ_(n)  (3) wherein: (a) Flu is a fluorenyl group substituted at at least the 2,7 position and the 3,6 position; (b) L is a substituted or an unsubstituted cyclopentadienyl group, a substituted or unsubstituted indenyl group, a substituted or unsubstituted fluorenyl group, or a heteroorgano group XR₂ in which X is a heteroatom from Group 15 or 16 of the Periodic Table, and R is an alkyl group, a cycloalkyl group or an aryl group containing from 1 to 20 carbon atoms; (c) B is a structural bridge between L and Flu imparting stereorigidity to the ligand structure (FluL); (d) M is a Group 4 or Group 5 transition metal; (e) Q is selected from the group consisting of Cl, Br, I, an alkyl group, an amino group, an aromatic group and mixtures thereof; and (f) n is 1 or
 2. 2. The metallocene component of claim 1 wherein the fluorenyl group Flu is substituted with substituents at the 2,7 positions which are bulkier than the substituents at the 3,6 positions.
 3. The metallocene component of claim 1 wherein the fluorenyl group Flu is substituted with an aryl group at each of the 2 and 7 positions and with a lower molecular weight substituent at each of the 3 and 6 positions.
 4. The metallocene component of claim 3 wherein said fluorenyl group Flu is substituted at each of the 2 and 7 positions with a phenyl or a substituted phenyl group and at each of the 3 and 6 positions with a bulky hydrocarbon group containing at least four carbon atoms.
 5. The component of claim 4 wherein said fluorenyl group Flu is substituted at each of the 3 and 6 positions with a tertiary butyl group.
 6. The metallocene component of claim 1 wherein said fluorenyl group Flu is substituted at each of the 2 and 7 positions with a C₁-C₃ alkyl group and at each of the 3 and 6 positions with a bulky hydrocarbon group containing at least 4 carbon atoms.
 7. The component of claim 5 wherein L is a heteroorgano group, XR₂ and wherein X is N, P, O or S, and R is an alkyl, cycloalkyl or aryl group.
 8. The component of claim 7 wherein X is N and R is a mononuclear aromatic group, or an alkyl or cycloalkyl group containing from 1 to 20 carbon atoms.
 9. The metallocene component of claim 1 wherein B(FluL)MQ_(n) is characterized by the formula:

wherein Ar is a phenyl group or substituted phenyl group.
 10. The metallocene component of claim 1 wherein B(FluL)MQ_(n) is characterized by the formula:

wherein: Ar is a phenyl group or a substituted phenyl group; and R is an alkyl group having from 1 to 20 carbon atoms or an aryl group having from 6 to 20 carbon atoms.
 11. The metallocene component of claim 1 wherein B(FluL)MQ_(n) incorporates a cyclopentadienyl group and is characterized by the formula:

wherein: Ar is a phenyl group or substituted phenyl group; R′ is a C₁-C₄ alkyl group or an aryl group; n is the number of substituents, from 0 to 4; E is a —C— group or an —Si— group; R₁ and R₂ are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group; M is titanium, zirconium or hafnium; and Q is chlorine, a methyl group or a phenyl group.
 12. The metallocene component of claim 11 wherein the cyclopentadienyl group is unsubstituted (n=0), a disubstituted cyclopentadienyl group (n=2) or a tetrasubstituted cyclopentadienyl group (n=4) wherein said metallocene component exhibits bilateral symmetry.
 13. The metallocene component of claim 11 wherein said cyclopentadienyl group is monosubstituted (n=1) or trisubstituted (n=3) wherein said metallocene component exhibits a non-bilateral symmetry.
 14. The metallocene component of claim 1 wherein B(FluL)MQ_(n) incorporates a cyclopentadienyl group and is characterized by the formula:

wherein: Ar is a phenyl group or substituted phenyl group; E is a —C— group or an —Si— group; R₁ and R₂ are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group; M is titanium, zirconium or hafnium; and Q is chlorine, a methyl group or a phenyl group.
 15. The metallocene component of claim 1 wherein B(FluL)MQ_(n) incorporates a cyclopentadienyl group and is characterized by the formula:

wherein: Ar is a phenyl group or substituted phenyl group; R₁ and R₂ are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group; E is a —C— group or an —Si— group; M is titanium, zirconium or hafnium; and Q is chlorine, a methyl group or a phenyl group.
 16. The metallocene catalyst component of claim 1 wherein B(FluL)MQ_(n) incorporates an indenyl group and is further characterized by the formula:

wherein: Ar is a phenyl group or substituted phenyl group; Ind is an indenyl or substituted indenyl group; E is a —C— group or an —Si— group; each of R₁ and R₂ is independently a hydrogen, a C₁-C₁₀ alkyl group, a cycloalkyl group or an aryl group; M is titanium, zirconium or hafnium; and Q is chlorine, a methyl group or a phenyl group.
 17. The metallocene component of claim 16 wherein said indenyl group is a tetrahydroindenyl group which is substituted or unsubstituted.
 18. The metallocene component of claim 17 wherein said indenyl group is an unsubstituted indenyl group or an unsubstituted tetrahydroindenyl group.
 19. The metallocene component of claim 1 wherein B(FluL)MQ_(n) is further characterized by the formula:

wherein: Flu is a fluorenyl or a substituted fluorenyl group; E is a —C— group or an —Si— group; each of R₁ and R₂ is independently a hydrogen, a C₁-C₁₀ alkyl group, a cycloalkyl group or an aryl group; M is titanium, zirconium or hafnium; and Q is chlorine, a methyl group or a phenyl group.
 20. The metallocene component of claim 19 wherein Flu is an unsubstituted fluorenyl group or a substituted fluorenyl group wherein the metallocene component exhibits bilateral symmetry.
 21. A process for the polymerization of an ethylenically unsaturated monomer comprising: (a) providing a metallocene catalyst component characterized by the formula: B(FluL)MQ_(n)  (3)  wherein: (i) Flu is a fluorenyl group substituted at at least the 2,7 positions and the 3,6 positions; (ii) L is a substituted or an unsubstituted cyclopentadienyl group, a substituted or unsubstituted indenyl group, a substituted or unsubstituted fluorenyl group, or a heteroorgano group XR₂ in which X is a heteroatom from Group 15 or 16 of the Periodic Table, and R is an alkyl group, a cycloalkyl group or an aryl group containing from 1 to 20 carbon atoms; (iii) B is a structural bridge between L and Flu imparting stereorigidity to the ligand structure (FluL); (iv) M is a Group 4 or Group 5 transition metal; (v) Q is selected from the group consisting of Cl, Br, I, an alkyl group, an amino group, an aromatic group and mixtures thereof; and (vi) n is 1 or 2; (b) providing an activating cocatalyst component; (c) contacting said metallocene component and said cocatalyst component in a polymerization reaction zone with an ethylenically unsaturated monomer under polymerization conditions to produce a polymer product by the polymerization of said monomer; and (d) recovering said polymer product from said reaction zone.
 22. The process of claim 21 wherein said monomer comprises propylene and said polymer product is a polypropylene homopolymer or copolymer.
 23. The process of claim 22 wherein said metallocene component of subparagraph (a) incorporates a cyclopentadienyl group and is characterized by the formula:

wherein: Ar is a phenyl group or substituted phenyl group; R₁ and R₂ are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group; R′ is a C₁-C₄ alkyl group or an aryl group; n is a number from 0 to 4; E is a —C— group or an —Si— group; each of R₁ and R₂ is a C₁-C₄ alkyl group; M is titanium, zirconium or hafnium; and Q is chlorine, a methyl group, a phenyl group, or a substituted phenyl or benzyl group.
 24. The method of claim 23 wherein said metallocene component exhibits bilateral symmetry and said polymer product is syndiotactic polypropylene.
 25. The process of claim 23 wherein said metallocene component incorporates a cyclopentadienyl group which is monosubstituted or trisubstituted to provide a metallocene component which does not exhibit bilateral symmetry and wherein said polymer product is an isotactic polypropylene.
 26. The process of claim 23 wherein said metallocene component incorporates a cyclopentadienyl group and is characterized by the formula:

and said polymer product is a syndiotactic polypropylene with a melting temperature higher than 170° C.
 27. The process of claim 23 wherein said polymer product is a syndiotactic polypropylene with a melting temperature higher than 150° C. and a crystallization temperature higher than 95° C.
 28. A method for the preparation of a bridged cyclopentadienyl fluorenyl metallocene structure comprising: (a) providing a 3,6-disubstituted fluorene characterized by the formula:

wherein: R is a branched alkyl group having from 1 to 20 carbon atoms or a cyclic alkyl having from 5 to 20 carbon atoms; (b) reacting said 3,6-disubstituted fluorene with a brominating agent to produce a 2,7-dibromo-3,6-disubstituted fluorene characterized by the formula:

(c) reacting said 2,7-dibromo-3,6-disubstituted fluorene in the presence of a palladium based catalyst with an arylboronic acid characterized by the formula:

wherein: Ar is a phenyl group or a naphthyl group; to produce a 2,3,6,7-substituted fluorene characterized by the formula:

or; (d) reacting said 2,7-dibromo-3,6-disubstituted fluorene with a magnesium or zinc-based Grignard reagent characterized by the formula: R′MX wherein: R′ is a C₁-C₂₀ alkyl, or a C₆-C₂₀ alicyclic or aryl group, M is magnesium or zinc, and X is a halogen, to produce a 2,7,3,6-tetrasubstituted fluorene characterized by the formula:

wherein: R′ and R are as defined above; and (e) reacting said 2,3,6,7-substituted fluorene with fulvene, which may be substituted or unsubstituted, to produce a bridged cyclopentadienyl fluorenyl ligand structure characterized by the formula:

wherein: R′ is a C₁-C₂₀ alkyl group or an aryl group; n is a number from 0-4; and R₁ and R₂ are each independently a hydrogen, a C₁-C₁₀ alkyl group or a cycloalkyl or an aryl group.
 29. The method of claim 28 wherein Ar is a phenyl group or substituted phenyl group.
 30. The method of claim 29 wherein R is a tertiary butyl group.
 31. The method of claim 28 wherein said fulvene is unsubstituted 6,6-dimethylfulvene to produce said methylene-bridged cyclopentadienylfluorenyl ligand structure in which n is
 0. 32. The method of claim 28 wherein said fulvene is unsubstituted 6-alkyl (or aryl) fulvene to produce said cyclopentadienylfluorenyl component with C(H)Alkyl or C(H)Aryl bridge in which n is
 0. 33. The method of claim 28 wherein said 3,6-disubstituted fluorene is a 3,6-di-tertiarybutylfluorene wherein said cyclopentadienylfluorenyl structure is characterized by the formula:

wherein: R′ is a C₁-C₂₀ alkyl group or an aryl group; and n is a number from 0 to 4; and R₁ and R₂ are each independently a hydrogen, a C₁-C₁₀ alkyl group, or a cycloalkyl group, or an aryl group.
 34. The method of claim 31 wherein said fulvene is substituted at the 2-position with a tertiary butyl group and at the 4-position with a methyl group, wherein said methylene-bridged cyclopentadienylfluorenyl ligand structure is characterized by the formula:

wherein: R′ is a C₁-C₄ alkyl group or an aryl group.
 35. The method of claim 34 wherein Ar is a phenyl group. 